Switching to github.com/bmizerany/pat for pattern matching.
Rethought the request struct. Made header fields actual http.Header types. Added version number.
Added request Arg context var. Fixed runtime middleware.
Adding AppEngine example.
Merge branch 'master' of github.com:cojac/tango

Conflicts:
	examples/helloworld/helloworld.go
	middleware_test.go